Radiotube



April 8, '1930.' c. F. w. BATES RADI OTUBE Filed June 16, 1927 Patented Apr. 8, 1930 r UNITED STATES PATENT? OFFICE ap ucaaon'nea June 15,

This invention relates to radio tubes, and particularly radio tubesespecially applicable for radio receiving purposes.

Various types of radio tubes have been designed for use on standard house line circuits, and various rectifiers have been de-' veloped for supplying the usual radio tubes with the filament or A battery voltage. Tubes which have been designed for use on house line currents have ordinarily been of the indirectly heated cathode type. Special A battery eliminators are expensive, bulky, and do not always successfully eliminate aripple or hum in the output current corre 6 sponding to the cycle frequency of the house line voltage;

According to the resent invention, there is provided a tube deslgned to operate on house line currents and which can be applied to 720' standardfreceiving circuits without modifications thereof, and with which no separate eliminator is required. Furthermore, the tube is so constructed as to eliminate or minimize the effect of the pulsations in the housesupply current. The tube is' of the directly heated filament or' cathode type, as

distinguished from. the indirectly. heated cathode type of tubes heretofore provided for operation on house lightin circults. 1

The invention may be rea y understood by reference to the accompanying drawings,

7 which illustrate one form of my invention,

- and in which Figure '1 is "a side elevation of a tube constructed in accordance with my invention;

Figure 2 is a detail view, which is some; what 7 diagrammatic, showing a section through the connector at the upper end .of the tube;

Figure 3 is a circuit diagram showing the manner in which the tube is connected with the source of operating voltage; and

Figure 4 is a diagramshowing a modified arrangement.

The tube as i llustrated comprises the usual envelope 2 mounted in a standard, base 3 having the usual connector pins 4 at the bottom thereof. Within the envelope 2, which is evacuated, is a stem 5. Passin through the stem-'5 in, the usual way is ale wire 6 which 1027. Serial n. males.

hook portion 10 that supports the upper en of a filament or cathode 11, the filament preferably being in the form of an inverted V. Three of the contact pins 4; on the base of the tube are connected with the wires 6, 8 and 10, respectivel ,in the manner that the filata ment plate an grid are ordinarily connected to the contact pins in a standard radio tube. One of the pins in the base is idle, not being connected with any of the electrodes.

Mounted on the upper end of the tube is a cap 12 of bakelite or other insulating material. The cap 12 has three contact pins thereon 13, 14 and 15. -Contact 13 is connected with. one end of the filament 11 at 16,'as best shown in Figures 2 and 3, and v connector 14 is connected with the other end of the filament at 17, the lead wires being brought in through a seal 18 in the top of the tube. 'The" center of the cathode, that is, the point which engages the arm 10', connects with the third connector 15 on the, cap. Within the cap across the connector-s13 and 14 is a .high resistance 19. This resistance i may be of any well known or preferred character. As shown, it is of the surface contact type made up of contacting disks pressed to gether. The pin 13 is connected 'tothe filament at 16 through a'rectifier 20 inside the cap 12. Pin 14 is connected with the other end of the filament through a similar rectifier 21. These rectifiers, which are of a verycompact nature, may be of any suitable. construction, such, for instance, as surface contact rectifiers of the typecomprising oxide coated disks pressed against other disks and capable of permitting 'a current flow in one direction only. These rectifiers have been only diagrammatically illustrated, 1 as themechanical construction thereof is well known and familiar to those skilled in the art. In view of the fact that the filament of the ordinary tube does not require more than one-fourth of an ampere, the rectifiers,

even 'to pass one-half an ampere,canbe'- very ing 24 is connected into, a standard house lighting circuit. The primary 22 is tapped 'at its centralpoint, and a .third wire connects the pin 15 with the central tap of the secondary of the transformer. This arrange-' ment is clearly shown in Figure 3.

With this arrangement, the central point of the filament may always be kept negative, while the ends of the filament are positive. A unidirectional current is thus supplied to each half of the cathode. The high resistance 19 connected across the circuit and tapped at its center, acts as a potentiometer, for the purpose of balancing the pulsating nature of the current supplied tothe filaments. By proper adjustment and regulation of this resistance, any ripple or distortion 1n the output current of the tube by reason of the pulsating nature of the current supplied to the filament, is substantially, if not entirely, eliminated. The potentiometer or high res1stance'19 can be set at the proper adjust- .ment in the factory when the tube is as sembled, and once the cap is applied to the tube, it cannot be changed thereafter.

In order to utilize the tubes in a standard radio recelving circuit, it is really necessary to remove the ordinary tubes and replace themwith tubes of the present type. It is also necessary to use a step-down transformer, and the central pin 15 in the cap of each of the tubes in theset is connected with the central tap on the secondary of the transformer, while the terminals 13 and 1 1 are connected with the opposite ends of the secondary of the transformer. The cost of the tubes is little more than the cost of the or dlnary tube, and the cost of the transformer is relativel small, so that a standard set can be change over for operation from a house hghtmg current easily and with relatively little expense. Furthermore, the change can be effected by anyone operating a set, since the wlrlng of the set does not have to be changed. To reduce the effect of the pulsating rectified current on the output of the tube, a C

I batte tions, this C battery to be used either alone or in combination with the high resistance 19.

In Figure 4 I have illustrated one such arrangement wherein-a C battery 19 is connected across the points 16 and 17 and to the negative lead wire 10 at 19". The capacity of may be connected across the filament .1n suc manner as to balance out the pulsamay be made therein within the contemplation of my invention and under the, scope of the following claims. I

I claim:

, l.-v The combination with a radio tube havl ing a base andhaving a filament, of a cap on the tube having three terminals thereon, one of the terminals being connected with the filament intermediate its ends, the other terminals being connected with the opposite ends of the filament, and a terminal on the base of the tube connected to the filament.

2. The combination with a radio tube having afilament, grid and plate, and having a base with contact pins leading to thefilament and plate, respectively, the filament pin being connected with the filament at a point intermediate its ends, of terminals at the top of the tube, one of which connects to one end of the filament, a second of which connects to the other end of the filament, and a third of which connects tothe filament intermediate its ends. I

3. The combination with a radio tube having a base and having a filament, of a cap on the tube with three terminals thereon, one of the terminals being connected to a central point the filament, the other two terminals being connected with the opposite ends thereof, and a high resistance within the cap connected across the last two terminals, the first terminal m'aln'ng contact with the high resistance intermediate its ends.

4. The combination with a radio tube having a filament, of two rectifiers mounted. on the tube and connected with opposite ends of the filament, one rectifier being in series with one end of the filament and one being in series with the other end of the filament,and a terminal connected with the filament. intermediate its'ends. O

5. The combination with a radio tube having a filament, of rectifiers mounted on the tube connected with opposite ends of the filament, a terminal connected with the filament intermediate its ends, and a high resistance connected across the rectifiers and to an intermediate point with which the said terminal makes contact.

6. The combinationzwith a radio tube having a base, an envelope and electrodes within the envelope including a filament, of terminals on the upper part of the tube leading to opposite ends of the filament, and a third terminal on the top of the tube leading to an intermediate point of the filament, and-a terminal in the base also connected with th filament.

7. The combination with a radio tubehav ing a base, an envelope and electrodes within the envelope including afilament, of

terminals on the upper part of the tube leading to opposite ends of the filament, a third terminal on the top of the tube leading to an intermediate point of the filament, and a high resistance at'the top of the tube'shunted across said first two terminals.

8. The combination with a radio tube having a base, an envelope and electrodes withi? the envelope including a filament, of terminals on the upper part of the tube leading to opposite ends of the filament, a third terminal on the top of the tube leading to an intermediate point of the filament, a high resistance at the top of the tube shunted across said first two terminals, and a rectifier between each of the first two terminals and the ends of the filament.

9. 'A radio tube including a base, an envelope on the base, electrodes within the envelope including a filament, a cap on the envelope having three terminals thereon, two of the terminals being connected. with opposite ends of the filament, a high resistance in the cap connecting said two terminals, and a rectifier in the cap between each of the first two terminals and the ends of the filament to which they are connected, the

third terminal being connected to the 'filahaving a base, an envelope and electrodes within the envelope including a filament, three terminals at the top of the envelope, two of which are joined to opposite ends of the filament, the third terminal being joined to a mid-point of the filament, and means including a source of direct current in series between the third terminal and the mid-point of the filament for balancing out pulsations in the filament voltage, and additional means for balancing out pulsations, comprising a high resistance connecting said first two terminals and having its mid-point connected with the third terminal. 7

In testimony whereof I have hereunto set my hand.

0. F. WILLIAM BATES.

ment intermediate the ends of the filament and being connected to an intermediate point of the high resistance.

10. A' radio tube comprising a base, an envelope, electrodes within the envelope including a filament, of rectifying means on the top of the envelope for supplying rectified direct current to opposite ends of the filament, and a resistance connected across said means to balance the pulsations m the rectified current.

11. The combination with a radio tube having a base, an envelope and electrodes within the envelope including a filament, of a rectifying means located on the top of the tube for supplying a pulsating current to opposite ends of the filament, and means carv the filament, a rectifier at the top of the tube in series with each of the first two lead wires, and a resistance connected across the first two lead wires, said negative lead wire being connected to the resistance at an intermediate point.

13. The combination with a radio tube having a base, an envelope and electrodes within the envelope including a filament, three terminals at the tpp of the envelope, two of 

